1. Field of Invention
The present invention generally relates to the field of merchandise security, and more particularly, to a system and method for alarming security tags using low profile and low power field projectors that can be easily installed at various locations in and around a business environment.
2. Description of Related Art
One way of providing security for merchandise in a retail facility is the use of traditional electronic article surveillance (EAS) systems. System systems include a transponder affixed to each article of merchandise to be protected and an EAS detection gate. See U.S. Pat. Nos. 4,692,747 (Wolf) and 4,831,363 (Wolf). The transponder normally takes the form of an electromagnetically responsive element enclosed in a plastic label, paper tag, sleeve of fabric, or hard plastic case. The responsive element may be a strip of ferromagnetic material, a section of acoustomagnetostrictive metallic glass, a parallel resonant circuit made with a capacitor and an inductor, or a strip antenna connected to a diode. These technologies, termed EM, AM, RF, and microwave, respectively, normally operate at a characteristic frequency determined by a combination of, regulatory, and historical reasons. The detection device consists of an antenna connected to both a transmitter and a receiver. The transmitter is arranged to provide a stimulating signal to the transponder element. The receiver is arranged to determine whether a transponder element of the requisite type is near the detector. Typically, detection devices are used to sound an alarm if a transponder is detected by a device located at a point of egress. When merchandise is purchased, EAS transponders may either be removed or deactivated by the application of special electromagnetic fields.
Traditional EAS provides several advantages. First, for EM, AM, and RF EAS, the detection device antenna is normally quite large and, as such, presents a visual deterrent to would-be malefactors. Next, when the detection devices are placed at points of egress, the retail facility operator can allow shoppers to freely handle and move merchandise within the store with the certainty of knowing that any attempt to remove merchandise from the facility prior to purchase will result in an alarm.
Traditional EAS however has several disadvantages. The detection systems are relatively expensive to buy. Worse, their installation can be costly since it often requires “trenching,” i.e., cutting channels into concrete flooring, to facilitate power wiring. Further, EAS detection systems require careful installation and routine maintenance because the signals from the transponders are of very low amplitude: only a small portion of the transmitted power reaches the transponder, and only a small portion of the energy reflected by the transponder reaches the receiver. As a result, retail facilities limit where they install and maintain EAS detection gates.
Three-Alarm EAS Transponders
At one extreme, an EAS transponder may consist solely of an electromagnetically responsive element which is embedded in an article of merchandise. At the other extreme, the transponder may be a complex assembly encompassing not just the responsive element, but also tamper detection and alarm sounding mechanisms. In addition, the transponder may be equipped with sensing circuitry capable of detecting the transmission of the EAS detection gate, and sound an alarm accordingly. A transponder equipped with all these features provides three means for sounding an alarm indicative of mishandling of merchandise:                (a) an alarm sounded by the EAS detection gate when the responsive element is nearby;        (b) an alarm sounded by the transponder itself when tampering is detected; and        (c) an alarm sounded by the transponder when the EAS detection gate is nearby.        
See also U.S. Pat. Nos. 7,663,489 (Scott, et al.); 7,538,680 (Scott, et al.); and 7,474,215 (Scott, et al.), directed to three-alarm transponders and all of whose entire disclosures are incorporated by reference herein.
These transponders may be affixed to or embedded with articles of merchandise in a variety of ways. Like ordinary EAS transponders, they may be embedded inside the merchandise itself or within the packaging for merchandise. They may be affixed permanently to the merchandise as by a permanent adhesive, lanyard, rivet, etc. Preferably they are detachably affixed via a mechanism which remains locked prior to sale and is unlocked post-sale by either the customer or the sales associated. Common means include the use of spring-clutch arrangements susceptible to opening via magnetic means or electronic means.
These transponders have the advantage of sounding an alarm anywhere that an improper attempt to is made to remove the transponder from the article of merchandise, e.g., in a fitting room or restroom, even where there is no detection device. In addition, such transponders may detect an improper removal of protected merchandise from a retail facility by sensing the proximity of an EAS detection gate, even when the return signal from the transponder to the EAS detection gate is too attenuated to allow the EAS detection gate to alarm.
These transponders can also be arranged to alarm only when the received stimulus signal includes special characteristic, such as amplitude, frequency, phase, or code modulated identifier. Such modulations can be impressed upon a base EAS transmission signal.
The following references are just a few examples of security tag systems wherein an alarm is included within the security tags themselves.
U.S. Pat. No. 4,851,815 (Enkelmann), whose entire disclosure is incorporated by reference herein, discloses a system for monitoring merchandise in a retail environment that utilizes a security tag which includes an alarming mechanism therein. The alarm is activated if (1) a loop which attaches the security tag to the merchandise is severed or if a casing associating with the merchandise is opened; or (2) if an alarm code from a transmitter is received by the security tag. The system also includes a means for transmitting a “clear code” that deactivates the alarm when appropriate.
DE 198 22 670 (Rapp), whose entire disclosure is incorporated by reference herein, discloses three different configurations of a system for monitoring merchandise using security tags that includes alarms therein. In a first embodiment of the system, the security tag alarm remains silent as long as the security tag (and the merchandise associated therewith) receiver is receiving particular transmitted signals at regular intervals in a particular zone; departure beyond this zone results in loss of the transmitted signals and therefore the activation of the security tag alarm. In a second embodiment, entry into another zone results in the security tag receiver receiving a signal that causes the alarm to activate. A third embodiment combines the features of both the first and second embodiments.
GB 2 205 426 (Yamada), whose entire disclosure is incorporated by reference herein, discloses a container case for housing a commodity (e.g., CD-ROM, DVD, etc), wherein the container case includes a removal detector, alarm and transmitter. Should a would-be thief attempt to remove the commodity from the container case without purchasing the commodity, the alarm in the container case is activated and a signal is transmitted to a remotely-located receiver and alarm. In addition, if a would-be thief attempts to exit the retail establishment with the commodity inside the container case without purchasing the commodity, an exit gate activates the container case alarm and the container case also transmits a signal to the remotely-located receiver and alarm. Also, another embodiment replaces the container case with an element that includes a loop for coupling to the commodity and wherein the element electronics includes a detector for detecting and alarming when the loop is severed.
Benefit Denial
One alternative to traditional EAS is the use of so-called benefit denial devices. Typically, these devices are plastic housings that are detachably affixed to merchandise. They are removed at the time the merchandise is purchased. The housing may enclose a tamper detection device, such as a sounding alarm, or a tamper detriment element such as a vial of ink. Attempting to remove the benefit denial device will result in the alarm sounding or ink spilling on the culprit, the merchandise, or both.
Benefit denial devices do serve as a visual deterrent to theft. However, they suffer from the disadvantage of not being detectable at a distance electronically. Thieves are often able to remove merchandise to a restroom or a quite corner of a store and there apply special tools to remove the tag. Alternatively, they may remove merchandise from the store without sounding an alarm and remove the device later at their leisure.
In view of the foregoing, though, there still remains a need for implementing an EAS transponder system/method that utilizes a low power and a low profile EAS beacon that can be easily and quickly installed in almost any desired location in a business environment.